The document discusses the composition and layers of the Earth's atmosphere. It notes that the atmosphere contains the air we breathe, helps retain heat, protects from radiation, and regulates climate. The atmosphere does not have a clear boundary with space but gradually thins. It is described as a protective layer sheltering all life. The document then outlines the major layers of the atmosphere from lowest to highest: the troposphere, where weather occurs; the stratosphere containing protective ozone; the mesosphere where meteorites burn up; the thermosphere containing the ionosphere which helps radio transmission; and the exosphere where light gases escape into space.

1. ATMOSPHERE
(Class-7 geography)
Presentation by-deepika thakur

2. TABLE OF CONTENT
Composition of atmosphere Layers of atmosphere

3. WHAT DO YOU MEAN BY ATMOSPHERE?
The atmosphere:
❯ contains the air that we breathe
❯ helps retain the sun’s heat and prevents it from
escaping back into space
❯ protects life from harmful radiation from the sun
❯ plays a major role in Earth’s water cycle
❯ helps keep the climate on Earth moderate
❯ There is no boundary between the atmosphere and outer
space. The atmosphere gets less dense and denser until it
“blends” into outer space.
“Atmosphere is a protectiv
layer of gases that shelter
all life on Earth, keeping
temperatures within a
relatively small range and
blocking out harmful rays
of sunlight.”

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6. Troposphere: This layer is the most important layer
of the atmosphere. Its average height is 13 km.
The air we breathe exists here.
Almost all the weather phenomena like rainfall, fog and
hailstorm occur in this layer.

7. Stratosphere: Above the troposphere lies the
stratosphere. It extends up to a height of 50 km. This layer is
almost free from clouds and associated weather
phenomenon, making conditions most ideal for flying
airplanes. One important feature of stratosphere is that it
contains a layer of ozone gas.

8. Mesosphere: This is the
third layer of the atmosphere. It lies above the
stratosphere. It extends up to the height of 80 km.
Meteorites burn up in this layer on entering from
the space.

9. Thermosphere : In thermosphere temperature
rises very rapidly with increasing height. Ionosphere is a
part of this layer. It extends between 80-400 km. This layer
helps in radio transmission. In fact, radio waves transmitted
from the earth are reflected back to the earth by this layer.

10. Exosphere: The upper
most layer of the
atmosphere is known as
exosphere. This layer has
very thin air. Light gases
like helium and hydrogen
float into the space from
here.

11. THANK YOU
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